Plague of Rust is a hex with a range of 24". The target's armour save is lowered by one point for the rest of the game (e.g. a model with light armour and shield will only have a 6+ save.) Plague of Rust can be repeatedly cast on the same target, reducing its armour save by a further -1 each time. The Wizard can choose to extend the range of this spell to 48". If he does so, the casting value is increased to 10+.